PICTURES: Canon lens EF 28-135 f/3.5-5.6 IS USM

I got a Canon EOS 20D since April 2005, completed by an ultrawide-angle lens, the Canon EF 17-40 f/4.0L USM. This lens is absolutely great, but it is an ultrawide-angle, and sometimes you need a more flexible lens, which you can use as a zoom, for example. After some on-line researches (how did we realize that *before* the web??), I decided myself for a Canon EF 28-135 f/3.5-5.6 IS USM.

How it looks like

Canon EF 28-135

Specs

f/3.5-5.6 maximum aperture

Micro UltraSonic Motor (USM)

Image Stabilizer

EF mount; standard zoom lens

Internal focusing; full-time manual focus; aspherical lens

28-135mm focal length

Closest Focusing Distance: 0.5m

Weight: 500g

The rule of thumb of a correct IS usage

The rule of thumb to get crisp photos without image stabilization is that your shutter speed should not be longer than 1 over your focal length. So if you are taking a picture zoomed in at 135mm, your shutter speed needs to be 1/135 sec or faster, and since no camera I know of has a 1/135 setting, that means going up to 1/160 sec (on cameras with stops in 1/3 increments) or faster. The image stabilizer means that you can go 2 f-stops slower than you normally could using the rule I just explained. So if you’re shooting at 135mm and you have the IS switched on, you can shoot at 1/40 sec instead of 1/160 sec. That means four times as much light goes past the shutter, or that you can get the same quality results with 1/4 of the ambient light you would normally need.